Some Properties of Rubber Latex

1938 ◽  
Vol 11 (3) ◽  
pp. 479-481
Author(s):  
Ernst Schmidt ◽  
Paul Stamberger
Keyword(s):  
Aqueous Phase ◽  
Electrophoretic Deposition ◽  
Distilled Water ◽  
Cent Solution ◽  
Rubber Latex ◽  
Rubber Particles ◽  
Serum Components

Abstract Rubber latex of the commercial type preserved by ammonia was freed almost completely of its serum components by a method involving two steps: 1. Electrophoretic deposition of the rubber particles on a membrane, followed by 2. Dispersion of the resultant paste in a 0.6-per cent solution of ammonia in distilled water. This process was repeated until the aqueous phase obtained from this separation was free of non-rubber components in the latex.

The Creaming of Hevea Latex by Colloids

1938 ◽  
Vol 11 (4) ◽  
pp. 608-623
Author(s):  
C. F. Vester
Keyword(s):  
Negative Charge ◽  
Dispersed Phase ◽  
Rubber Content ◽  
Rubber Latex ◽  
Ionogenic Groups ◽  
Rubber Particles ◽  
Dispersing Medium ◽  
Almost All ◽  
Short Time ◽  
Serum Components

Abstract Hevea latex is generally considered to be a suspension of rubber particles of various dimensions up to about 3 µ. The rubber hydrocarbon contains no “ionogenic groups,” and it is believed that part of the serum components imparts a negative charge to the rubber particles. Almost all latex imported into Europe is preserved by means of 0.5 to 0.7 per cent of ammonia. This ammonia plays a three-fold part: (1) it prevents premature souring of the latex; (2) it increases somewhat the charge on the particles; and (3) it attacks all types of serum components so that within a short time the “preserved” latex is hardly comparable with natural latex. As with all suspensions in which the dispersed phase is lighter than the dispersing medium, rubber latex exhibits the phenomena of creaming. The density of the rubber particles is approximately 0.914, that of the medium, 1.020. By means of creaming, it is possible to obtain a latex (1) which has a higher rubber content, whereby transportation space and cost are saved, and (2) which contains no components having a tendency to deposit a sediment. The natural creaming of latex, which is of no importance technically, was observed by Faraday as early as 1825.

The State of Polydispersion of Hevea Latex. I

1946 ◽  
Vol 19 (1) ◽  
pp. 176-186
Author(s):  
J. H. E. Hessels
Keyword(s):  
Protein Content ◽  
Hevea Brasiliensis ◽  
The State ◽  
Rubber Content ◽  
Rubber Latex ◽  
Latex Particles ◽  
Rubber Particles ◽  
The Subject ◽  
Points Of View ◽  
Good Agreement

Abstract The rubber particles in the latex of Hevea brasiliensis are present in the form of a polydispersion, and their diameters lie within the range of 0.1 to 3 microns. The rubber hydrocarbon itself is composed of a mixture of macromolecules of different degrees of polymerization. Rubber latex is, therefore, a system which is at the same time both polydispersed and polymolecular. It is well known that the degree of dispersion of a substance governs to a great extent certain properties of the substance. Moreover, astonishing as it may seem, in the great number of investigations which have been made of the composition and properties of latex and crude rubber, almost no attention has been paid to the part which may be played by the dimensions of the latex particles. However, in an investigation concerned with the centrifugation of latex, Loomis and Stump have called attention to this possibility, and in a study of latex obtained by fractionation, and in which the majority of the latex particles were of large dimensions, McGavack came to the conclusion that the protein content is proportional to the surface area of the globules. This limited knowledge of the subject seemed to warrant a more thorough study of the problem, which is of fundamental importance both from the theoretical and practical points of view. The investigation as a whole divided itself into three essential parts: (1) separation of latex into fractions containing particles of different sizes, and measurement of the state of dispersion in these fractions, (2) a study of the relation of these fractions to the composition of the rubber, i.e., the relation between the content of nonrubber components and the size of the latex particles, and (3) a study of the changes in the properties of the rubber hydrocarbon with change in the size of the latex particles. The latex used in this investigation was ordinary latex, containing 38–40 per cent dry-rubber content and preserved with ammonia. For the most important points, a concentrated latex (creamed latex containing 60 per cent dry-rubber content) was also tested. These two latices were about two years old when the investigation was started, and they gave results which were in good agreement with each other. In the present paper, only the data obtained with the first of the two latices are presented.

scholarly journals INFLUENCE OF THE CONCENTRATION OF ELECTROLYTES ON SOME PHYSICAL PROPERTIES OF COLLOIDS AND OF CRYSTALLOIDS

1920 ◽  
Vol 2 (3) ◽  
pp. 273-296 ◽  
Author(s):  
Jacques Loeb
Keyword(s):  
Physical Properties ◽  
Osmotic Pressure ◽  
Initial Rate ◽  
Charged Particles ◽  
Distilled Water ◽  
Neutral Salt ◽  
Gelatin Solution ◽  
Acid Salt ◽  
Cent Solution ◽  
Depressing Effect

1. When a 1 per cent solution of a metal gelatinate, e.g. Na gelatinate, of pH = 8.4 is separated from distilled water by a collodion membrane, water will diffuse into the solution with a certain rate which can be measured by the rise of the level of the liquid in a manometer. When to such a solution alkali or neutral salt is added the initial rate with which water will diffuse into the solution is diminished and the more so the more alkali or salt is added. This depressing effect of the addition of alkali and neutral salt is greater when the cation of the electrolyte added is bivalent than when it is monovalent. This seems to indicate that the depressing effect is due to the cation of the electrolyte added. 2. When a neutral M/256 solution of a salt with monovalent cation (e.g. Na2SO4 or K4Fe(CN)6, etc.) is separated from distilled water by a collodion membrane, water will diffuse into the solution with a certain initial rate. When to such a solution alkali or neutral salt is added, the initial rate with which water will diffuse into the solution is diminished and the more so the more alkali or salt is added. The depressing effect of the addition of alkali or neutral salt is greater when the cation of the electrolyte added is bivalent than when it is monovalent. This seems to indicate that the depressing effect is due to the cation of the electrolyte added. The membranes used in these experiments were not treated with gelatin. 3. It can be shown that water diffuses through the collodion membrane in the form of positively charged particles under the conditions mentioned in (1) and (2). In the case of diffusion of water into a neutral solution of a salt with monovalent or bivalent cation the effect of the addition of electrolyte on the rate of diffusion can be explained on the basis of the influence of the ions on the electrification and the rate of diffusion of electrified particles of water. Since the influence of the addition of electrolyte seems to be the same in the case of solutions of metal gelatinate, the question arises whether this influence of the addition of electrolyte cannot also be explained in the same way, and, if this be true, the further question can be raised whether this depressing effect necessarily depends upon the colloidal character of the gelatin solution, or whether we are not dealing in both cases with the same property of matter; namely, the influence of ions on the electrification and rate of diffusion of water through a membrane. 4. It can be shown that the curve representing the influence of the concentration of electrolyte on the initial rate of diffusion of water from solvent into the solution through the membrane is similar to the curve representing the permanent osmotic pressure of the gelatin solution. The question which has been raised in (3) should then apply also to the influence of the concentration of ions upon the osmotic pressure and perhaps other physical properties of gelatin which depend in a similar way upon the concentration of electrolyte added; e.g., swelling. 5. When a 1 per cent solution of a gelatin-acid salt, e.g. gelatin chloride, of pH 3.4 is separated from distilled water by a collodion membrane, water will diffuse into the solution with a certain rate. When to such a solution acid or neutral salt is added—taking care in the latter case that the pH is not altered—the initial rate with which water will diffuse into the solution is diminished and the more so the more acid or salt is added. Water diffuses into a gelatin chloride solution through a collodion membrane in the form of negatively charged particles. 6. When we replace the gelatin-acid salt by a crystalloidal salt, which causes the water to diffuse through the collodion membrane in the form of negatively charged particles, e.g. M/512 Al2Cl6, we find that the addition of acid or of neutral salt will diminish the initial rate with which water diffuses into the M/512 solution of Al2Cl6, in a similar way as it does in the case of a solution of a gelatin-acid salt.

Improved Deproteinization Process for Protein-Free Natural Rubber Latex

2013 ◽  
Vol 844 ◽  
pp. 474-477 ◽  
Author(s):  
Wiwat Pichayakorn ◽  
Jirapornchai Suksaeree ◽  
Wirach Taweepreda
Keyword(s):  
Natural Rubber ◽  
Negative Charge ◽  
Ph Value ◽  
Natural Rubber Latex ◽  
Solid Content ◽  
Enzyme Treatment ◽  
Distilled Water ◽  
Rubber Latex ◽  
Total Solid Content ◽  
Leaching Process

Hev b1-14 type proteins in natural rubber latex (NRL) have been identified as allergens in immunogenic responses. Several methods have been developed to reduce these proteins from NRL such as enzyme treatment, centrifugation, creaming, simple or ultrasonic leaching, and chlorination. In this work, the improvement of deproteinization of NRL was developed using the combination of enzyme treatment and leaching processes. The fresh NRL was incubated with 0.2 phr proteolytic alcalase enzyme, and preserved with 2%v/v paraben concentrate in the presence of a 2%v/v sodium lauryl ether sulfate (SLES) as a surfactant at 37°C for 24 hours, and then centrifuged. The upper rubber mass was then leached for three times with either distilled water, a 1%v/v SLES solution, or a mixture of 1%v/v SLES and 2.5%v/v ethanol, and then finally re-dispersed in distilled water. It was found that the increasing process of leaching with either 1%v/v SLES or a mixture of 1%v/v SLES and 2.5%v/v ethanol had the higher efficacy to reduce the remained protein in deproteinized NRL (DNRL). The best deproteinized process was the enzyme treatment and followed by the three times leaching process with a mixture of 1%v/v SLES and 2.5%v/v ethanol, that could completely reduce the proteins in DNRL to 0%. This DNRL had the pH value, viscosity, dry rubber content, and total solid content of 7.41, 13.82 cps, 42.57%, and 44.63%, respectively. Its particle size was 626.23 nm with low polydispersity index of 0.16. The negative charge of SLES could increase the higher negative charge of DNRL to-63.20 mV that exhibited very good physical stability during storage. In conclusions, the combination of enzyme treatment and leaching process with both SLES and ethanol was successful to produce the protein-free DNRL. This DNRL could be further used for several applications including medical skin products.

scholarly journals Use of a Glucose Bismuth Sulphite Iron Medium for the Isolation of B. typhosus and B. proteus

1927 ◽  
Vol 26 (4) ◽  
pp. 374-391 ◽  
Author(s):  
W. James Wilson ◽  
E. M. Mcv. Blair
Keyword(s):  
Sodium Phosphate ◽  
Inhibitory Action ◽  
Brilliant Green ◽  
Ferrous Sulphate ◽  
Sodium Sulphite ◽  
Distilled Water ◽  
Cent Solution ◽  
Bismuth Citrate ◽  
The Media ◽  
Made In

1. The development and use of a medium which has selective properties for the growth of B. typhosus and B. proteus is described.2. The principle of the method rests (1) on the positive property of the B. typhosus of being able to reduce a sulphite to a sulphide in the presence of glucose, (2) on the inhibitory action on the growth of B. coli of a bismuth sulphite in the presence of a certain excess of sodium sulphite.3. The media finally developed are made in the following way:A. To 100 c.c. of a melted 3 per cent. nutrient agar are added 5 c.c. of a 20 per cent. solution of glucose, 10 c.c. of a 20 per cent. solution of sodium sulphite (anhydrous), 5 c.c. of a standard bismuth solution. After boiling for two minutes an addition is made of 1 grm. of exsiccated sodium phosphate and 1 c.c. of an 8 per cent. solution of ferrous sulphate crystals.Medium B is the same as above with the addition of 0·5 c.c. of a 1 per cent. watery solution of brilliant green. The standard liquor bismuthi is prepared by mixing 60 grm. bismuth citrate with 50 c.c. of distilled water and then with 20 c.c. liq. ammonii sp. gr. 0·880 and finally making the volume up to 500 c.c. with distilled water.4. On these media the B. typhosus grows readily and forms flat blackdry surface colonies. B. proteus grows on the medium in a non-spreading fashion but does not form black colonies. B. coli either fails to grow or after a period of inhibition forms brown sticky raised colonies.5. Bismuth media were used in the examination of 31 enteric stools and in 30 instances the infecting microorganism was successfully isolated. Single examinations only were made and the material was usually 24 to 48 hours old at the time of examination.6. Emulsions of enteric stools which as shown by the usual media contained only a dozen or so of typhoid bacilli were found by our bismuth media actually to contain several thousand.7. The isolation from a case of typhoid fever of a proteus X 19 strain is recored.8. As regards its growth on bismuth sulphite media B. paratyphosus B behaves more like a reducing B. coli than a B. typhosus culture. For the isolation of B. paratyphosus B a lactose bile salt brilliant green medium is described.

Anode Process for Rubber Articles and Coatings

1933 ◽  
Vol 6 (4) ◽  
pp. 537-548 ◽  
Author(s):  
C. L. Beal
Keyword(s):  
Organic Compounds ◽  
Alkaline Medium ◽  
Colloidal Particles ◽  
Water Phase ◽  
Inorganic Salts ◽  
Brownian Movement ◽  
Rubber Latex ◽  
Butter Fat ◽  
Rubber Particles ◽  
Anode Process

Abstract THE term “anode process” has been chosen and used widely in the trade to designate a fundamental method for the production, directly from rubber latex, rapidly, and in one application, of articles and coatings of the highest grade of unmasticated rubber. Rubber latex, a milky exudation from the bark of rubber trees, is composed chiefly of tiny particles of rubber suspended in a water phase or serum, not unlike globules of butter fat in milk. Rubber latex contains small amounts of many organic compounds and inorganic salts. Some of these non-rubber materials, such as the proteins and resins, are considered to be adsorbed on the surfaces of the rubber particles and to be responsible for many of the colloidal characteristics of latex. As it comes from the tree, the latex is unstable and coagulates easily, but, when stabilized with ammonia, it can be safely shipped and stored for long periods. Like most colloidal particles in suspension in an alkaline medium, the rubber particles of ammoniated latex are negatively charged through the adsorption of hydroxyl anions. The particles, many as small as 1/25,000 inch in diameter, are in constant oscillation (Brownian movement) and are kept from hitting one another and sticking together (coagulating) by the repulsion of their electric charges. When the hydroxyl ions are neutralized or otherwise removed from the particles, the electric repulsion between particles disappears and coagulation results.

A Vulcanization of Rubber Latex by Potassium Ferricyanide

1937 ◽  
Vol 10 (4) ◽  
pp. 762-767
Author(s):  
D. Spence ◽  
J. D. Ferry
Keyword(s):  
Potassium Ferricyanide ◽  
Rubber Latex ◽  
Oxidizing Agents ◽  
Serum Components

Abstract (1) Vulcanization of rubber is produced by heating latex, from which the diffusible serum components have been removed, with potassium ferricyanide in the absence of air. (2) In the course of the treatment, the ferricyanide is reduced to ferrocyanide. (3) A similar effect may be produced by certain other metallic oxidizing agents in the absence of air.

The Proteins in Preserved Hevea Latex

1938 ◽  
Vol 11 (4) ◽  
pp. 601-607 ◽  
Author(s):  
C. Bondy ◽  
H. Freundlich
Keyword(s):  
Aqueous Solutions ◽  
Electrophoretic Mobility ◽  
Isoelectric Point ◽  
Pure Water ◽  
Protein A ◽  
Distilled Water ◽  
Latex Particles ◽  
Rubber Particles ◽  
Protein B

Abstract 1. Two proteins were isolated from preserved Hevea latex. 2. The proteins were distinguished by their electrokinetic behavior and their solubilities in aqueous solutions and in alcohol. Protein A has an isoelectric point at pH 4.55; it is insoluble in distilled water and alcohol. Protein B has an iso-electric point at pH 3.9; it is soluble in pure water and strong (70 per cent) alcohol. 3. A comparison of the electrophoretic mobility of the latex particles as function of the pH with the corresponding curves of the proteins confirms the result of previous investigators that a coating of the rubber particles by proteins is decisive for their behavior. In a range of pH between 5.5 and 8 the curve of the latex particles is practically identical with that of protein A.

Preparation of Highly Purified Hevea Rubber

1949 ◽  
Vol 22 (3) ◽  
pp. 731-734 ◽  
Author(s):  
G. T. Verghese
Keyword(s):  
Mechanical Treatment ◽  
New Method ◽  
Rubber Latex ◽  
Rubber Particles ◽  
High Degree

Abstract A new method is described by which rubber hydrocarbon of a high degree of purity can be obtained without resorting to any drastic chemical or mechanical treatment of the rubber. Rubber latex is treated with ammonium oleate, which displaces the proteins from the surface of the rubber particles. The displaced proteins, along with other nonrubber substances present in the serum, are removed by repeated creaming of the latex. Finally, the creamed latex is “solubilized” in n-hexane, and the rubber precipitated by adding acetone.

Some Applications of High-Frequency Electric Currents to the Latex Industry

1938 ◽  
Vol 11 (3) ◽  
pp. 570-574
Author(s):  
Henri Leduc
Keyword(s):  
Dielectric Loss ◽  
Electric Field ◽  
Electric Fields ◽  
High Frequency ◽  
Specific Effect ◽  
Entire Body ◽  
Rubber Latex ◽  
Joule Effect ◽  
High Frequency Electric Field ◽  
Rubber Particles

Abstract The “radiocoagulation” of latex has been developed in the laboratories of L'Office National des Recherches et Inventions by Dufour and Leduc, who conceived the idea of applying the effect of electric fields of high frequency to rubber latex. When latex is exposed to the action of an electric field of high frequency, the entire body of liquid is heated uniformly, provided that the electric field itself is uniform. The causes of this heating effect are difficult to ascertain because various phenomena are involved simultaneously, e. g., a dielectric loss in the rubber and a loss by the Joule effect in the serum. Each of these effects is, according to conditions, the predominant one, e. g., by increasing the conductivity of the serum, electrolytes such as sodium sulfate or ammonium sulfate increase the Joule loss, U2/R, whereas an increase in the concentration of latex tends to increase the dielectric loss. Finally, since rubber particles are not electrically neutral, they are subject to alternating forces of the electric field, which is a specific effect of the high frequency, and these forces impart to the rubber particles movements throughout the liquid. Now latex can be rendered sensitive to mechanical forces, i. e., some mixtures can be coagulated by slight agitation. Accordingly it is conceivable that a high-frequency electric field, by setting the rubber particles in motion throughout the emulsion, is capable of coagulating a mass of latex exposed to the field.

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